Hydraulic damping device

ABSTRACT

This hydraulic damping device comprises a cylinder for containing oil; a reservoir chamber R which is provided in the outer part of the cylinder and in which liquid accumulates; a piston provided so as to be axially movable within the cylinder and dividing the space within the cylinder into a first oil chamber and a second oil chamber, which contain oil; a baffle member provided as a separate element from the cylinder, the baffle member having a body which is provided in the reservoir chamber R, and also having a protrusion which protrudes from the body, the baffle member preventing the waving of the surface of oil in the reservoir chamber R; and a limiting section (first section to be held) provided to the baffle member and limiting the movement of the baffle member on both one side and the other side in the axial direction.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. §371 of International Patent Application No. PCT/JP2017/009,317, filedMar. 8, 2017, and claims the benefit of Japanese Patent Application No.2017-040477, filed Mar. 3, 2017, all of which are incorporated herein byreference in their entirety. The International Application was publishedin Japanese on Sep. 7, 2018 as International Publication No.WO/2018/158964 under PCT Article 21(2).

FIELD OF THE INVENTION

The present invention relates to a hydraulic damping device.

BACKGROUND OF THE INVENTION

For example, the hydraulic damping device disclosed in Japanese PatentApplication Laid-Open Publication No. 2014-029201 includes a protrusionin a reservoir chamber or a protrusion on an outer cylinder projectingfrom its inner surface toward an inner cylinder, in order to preventruffle of the liquid surface and formation of bubbles. The protrusion isformed over the entire or almost entire circumference of the outersurface of the inner cylinder or the inner surface of the outercylinder. When viewed from the direction perpendicular to the outersurface or the inner surface, the protrusion assumes a wave-like shape.

Technical Problem

For example, when a liquid surface in the liquid reservoir ruffles, itcauses bubbles to mix into the liquid, which makes it difficult togenerate a desired damping force. One countermeasure to this would be toprovide a disturbance prevention member to prevent disturbance of theliquid surface in the liquid reservoir. However, when such a disturbanceprevention member is a separate component from the cylinder, thedisturbance prevention member may move during operation of the hydraulicdamping device. This may hinder the disturbance prevention member fromreliably preventing ruffle of the liquid surface, which may result in afailure to prevent mixing of bubbles into the liquid.

An object of the present invention is to reliably prevent mixing ofbubbles into the liquid in the hydraulic damping device.

SUMMARY OF THE INVENTION Solution to Problem

With this object in view, the present invention is a hydraulic dampingdevice including: a cylinder unit storing liquid; a liquid reservoiroutside the cylinder unit, the liquid reservoir retaining liquid; apartitioning unit configured to move in an axial direction inside thecylinder unit, the partitioning unit partitioning a space inside thecylinder unit into a first oil chamber and a second oil chamber eachstoring liquid; a disturbance prevention member separate from thecylinder unit, the disturbance prevention member including a main bodylocated in the liquid reservoir and a protrusion protruding from themain body, the disturbance prevention member being configured to preventdisturbance of a liquid surface of liquid within the liquid reservoir;and a restricting part provided to the disturbance prevention member,the restricting part being configured to restrict the disturbanceprevention member from moving to both one side and the other side in theaxial direction.

Advantageous Effects of Invention

According to the present invention, it is possible to reliably preventbubbles from mixing into the liquid in the hydraulic damping device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an entire view of a hydraulic damper of the first embodiment.

FIG. 2 is an entire view of a baffle member of the first embodiment.

FIGS. 3A and 3B are explanatory diagrams of the baffle member of thefirst embodiment.

FIGS. 4A and 4B are explanatory diagrams of how the hydraulic damper ofthe first embodiment works.

FIG. 5 is an explanatory diagram of a baffle member of the secondembodiment.

FIG. 6 is an explanatory diagram of a baffle member of the thirdembodiment.

FIGS. 7A and 7B are explanatory diagrams of a baffle member of thefourth embodiment.

FIGS. 8A and 8B are explanatory diagrams of a baffle member of the fifthembodiment.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below in detailwith reference to the attached drawings.

First Embodiment Structure and Function of the Hydraulic Damper 1

FIG. 1 is an entire view of the hydraulic damper 1 of the firstembodiment.

As shown in FIG. 1, the hydraulic damper 1 (an example of the hydraulicdamping device) includes a cylinder unit 10 storing oil (an example ofthe liquid), and a rod 20. One end of the rod 20 is inserted into thecylinder unit 10 such that the rod 20 can slide within the cylinder unit10, and the other end of the rod 20 protrudes from the cylinder unit 10.The hydraulic damper 1 further includes a piston unit 30 disposed at theone end of the rod 20, a bottom valve unit 40 disposed at one end of thecylinder unit 10, a damping force changer 50 disposed outside of thecylinder unit 10 in the radial direction. The hydraulic damper 1 furtherincludes a baffle member 60.

In the following description, the longitudinal direction of thehydraulic damper 1 shown in FIG. 1 is referred to as an “axialdirection”. The lower side in the axial direction is referred to as “oneside”, and the upper side of the hydraulic damper 1 is referred to as“the other side”. Also, the lateral direction of the hydraulic damper 1shown in FIG. 1 is referred to as a “radial direction”. Further, theside radially closer to the centerline is referred to as an “inside inthe radial direction”, and the side radially away from the centerline isreferred to as an “outside in the radial direction”. Further, therotational direction of the hydraulic damper 1 about the axial directionis referred to as a “circumferential direction”.

Structure and Function of the Cylinder Unit 10

The cylinder unit 10 includes a cylinder 11 (an example of the firstcylinder), an outer cylinder body 12 (an example of the second cylinder)disposed at the outside of the cylinder 11 in the radial direction, anda damper case 13 (an example of the third cylinder) disposed at theoutside of the outer cylinder body 12 in the radial direction. Thecylinder unit 10 further includes a rod guide 14 at its other side end.

The cylinder 11 has a cylindrical shape and includes a cylinder opening11H at the other side. The cylinder 11 is contacted by the piston unit30 such that the piston unit 30 is movable in the axial direction.

The outer cylinder body 12 forms a communication path L between theouter cylinder body 12 and the cylinder 11. Also, the outer cylinderbody 12 includes an outer cylinder body opening 12H and a solenoidconnecting part 12J (an example of the connecting part) at positionsfacing the damping force changer 50. The solenoid connecting part 12Jincludes an oil flow path, and protrudes to the outside in the radialdirection for connection with the damping force changer 50.

The outer cylinder body 12 further includes a holding part 12P at theother side relative to the solenoid connecting part 12J. The holdingpart 12P protrudes to the outside in the radial direction. In thepresent embodiment, one (single) holding part 12P is provided.

In the present embodiment, during manufacture of the outer cylinder body12, a punching tool is pressed to the cylindrical outer cylinder body 12from the inside in the radial direction of the outer cylinder body 12.This forms the outer cylinder body opening 12H and the holding part 12Pin one process.

The damper case 13 forms a reservoir chamber R between the damper case13 and the outer cylinder body 12. The reservoir chamber R retains oil.Along with the movement of the rod 20 relative to the cylinder 11, thereservoir chamber R (an example of the liquid reservoir) absorbs oil inthe cylinder 11 (the first oil chamber Y1) or supplies oil into thecylinder 11 (the first oil chamber Y1). Further, the reservoir chamber Rretains oil flowing out of the damping force changer 50. The damper case13 includes a case opening 13H at a position facing the damping forcechanger 50.

The rod guide 14 closes the other side ends of the cylinder 11, theouter cylinder body 12, and the damper case 13. Further, the rod guide14 supports the rod 20 on the inside in the radial direction such thatthe rod 20 can slide in the axial direction.

Structure and Function of the Rod 20

The rod 20 is a rod-like member extending in the axial direction. Therod 20 connects to the piston unit 30 at the one side. Also, the rod 20connects to a vehicle body at the other side via a coupling member orthe like (not shown in the figure).

Structure and Function of the Piston Unit 30

The piston unit 30 (an example of the partitioning unit) includes apiston body 31 having multiple piston oil ports 311, a piston valve 32opening and closing the other side of the piston oil ports 311, a spring33 interposed between the piston valve 32 and the one side end of therod 20. The piston unit 30 partitions the oil chamber within thecylinder 11 into the first oil chamber Y1 (an example of the firstliquid chamber) and the second oil chamber Y2 (an example of the secondliquid chamber).

Structure and Function of the Bottom Valve Unit 40

The bottom valve unit 40 includes a valve seat 41, a damping valve 42 atthe one side of the valve seat 41, and a check valve 43 at the otherside of the valve seat 41. The bottom valve unit 40 provides a partitionbetween the first oil chamber Y1 and the reservoir chamber R.

Structure and Function of the Damping Force Changer 50

The damping force changer 50 (an example of the damping force generator)includes a solenoid unit 51, a connecting channel member 52, and asolenoid valve 55.

The solenoid unit 51 advances or retracts a plunger 51P based on controlby a controller (not shown in the figure).

The connecting channel member 52 is a substantially cylindrical memberhaving a connecting channel 52R inside thereof.

The solenoid valve 55 changes a cross-sectional area of oil flow withinthe connecting channel 52R by moving the position of the solenoid valve55 relative to the connecting channel member 52. Thus, the solenoidvalve 55 throttles the flow of oil within the connecting channel 52R.

In the first embodiment, damping force in the hydraulic damper 1 ismainly generated by throttling of the oil flow by the damping forcechanger 50.

Structure and Function of the Baffle Member 60

FIG. 2 is an entire view of the baffle member 60 of the firstembodiment.

FIGS. 3A and 3B are explanatory diagrams of the baffle member 60 of thefirst embodiment. FIG. 3A is a side view of the baffle member 60, andFIG. 3B is a cross-sectional view of the baffle member 60 taken alongthe line IIIB-IIIB in FIG. 3A.

As shown in FIG. 2, the baffle member 60 (an example of the disturbanceprevention member) is a substantially cylindrical member. The bafflemember 60 may be made of synthetic resin, for example.

The baffle member 60 includes a main body 61 and a disturbanceprevention part 62 disposed at the outside of the main body 61 in theradial direction. The baffle member 60 further includes a first heldpart 63, a second held part 64 (see FIGS. 3A and 3B), and a third heldpart 65 (see FIGS. 3A and 3B) at the one side. The baffle member 60extends in the axial direction.

The first held part 63, the second held part 64, and the third held part65 of the baffle member 60 of the first embodiment each serve as anexample of the restricting part.

The baffle member 60 is a separate component from the outer cylinderbody 12, so that the baffle member 60 can be attached to and detachedfrom the outer cylinder body 12. In the present embodiment, the bafflemember 60 is inserted in between the outer cylinder body 12 and thedamper case 13 and thereby attached to the outer cylinder body 12.

Main Body 61

The main body 61 has an inner diameter substantially equal to an outerdiameter of the outer cylinder body 12. Also, the main body 61 has anouter diameter smaller than an inner diameter of the damper case 13.

As shown in FIG. 3A, the main body 61 includes a slit 61S extending inthe axial direction. The slit 61S divides the main body 61 in thecircumferential direction of the main body 61.

Disturbance Prevention Part 62

As shown in FIG. 2, the disturbance prevention part 62 is disposed suchthat its substantially intermediate position in the axial directioncoincides with a liquid level of oil in 1G state (the state where astationary force acts on the hydraulic damper 1 with a vehicle equippedwith the hydraulic damper 1 in normal ground contact). The disturbanceprevention part 62 prevents ruffle (disturbance) of oil in the reservoirchamber R.

As shown in FIGS. 2 and 3A, the disturbance prevention part 62 includesmultiple (seven in the first embodiment) protrusions 621 that protrudefrom the outer surface of the main body 61 to the outside in the radialdirection. In the first embodiment, the protrusions 621 are arranged atsubstantially equal intervals in the axial direction.

The protrusion 621 closest to the other side is located at a positioncorresponding to an oil level at the maximum compression of thehydraulic damper 1. Also, the protrusion 621 closest to the one side islocated at a position corresponding to an oil level at the maximumextension of the hydraulic damper 1.

The baffle member 60 of the first embodiment 1 is structured such thatat least one protrusion 621 remains within the oil during changes in theliquid level of oil due to advance and retraction of the rod 20. Thisstructure is true of the baffle members of the other embodimentsdescribed later.

The outer diameter of each protrusion 621 is slightly smaller than aninner diameter of the damper case 13. This allows the oil to flowslightly between the disturbance prevention part 62 and the damper case13 in the axial direction.

The protrusions 621 may include cutouts 621K as shown by broken lines inFIGS. 2 and 3A.

In this case, the cutouts 621K are formed in the respective protrusions621 except for those closest to the one side and closest to the otherside.

Further, each of the cutouts 621K has a different width. Specifically,the cutouts 621K of the protrusions 621 closer to the other side have alarger width than those of the protrusions 621 closer to the one side.This allows the oil to gradually fall down to the one side when, forexample, the oil level rises to the other side of the disturbanceprevention part 62 and then descends.

Further, the cutouts 621K of two adjacent protrusions 621 do not faceeach other in the axial direction. That is, two adjacent protrusions 621are placed so that their cutouts 621K are displaced from each other inthe circumferential direction. In this way, the oil may detour in thecircumferential direction while flowing through the baffle member 60.

First Held Part 63

As shown in FIG. 2, the first held part 63 includes a first opening 631,a first neck part 632 at the one side of the first opening 631, a firstguide part 633 at the one side of the first neck part 632, and adeformation permission part 634 at a different position from the firstneck part 632 in the circumferential direction.

The first opening 631 is a substantially round opening. The firstopening 631 has a circumferential width W1 that is slightly larger thanan outer diameter D of the holding part 12P. In a state where the bafflemember 60 is attached to the outer cylinder body 12, the first opening631 restricts the baffle member 60 from moving to the one side.

Also, in the state where the baffle member 60 is attached to the outercylinder body 12, the first opening 631 restricts the baffle member 60from moving in the circumferential direction.

The first neck part 632 has a circumferential width W2 that is smallerthan the outer diameter D of the holding part 12P. In the state wherethe baffle member 60 is attached to the outer cylinder body 12, thefirst neck part 632 restricts the baffle member 60 from moving to theother side relative to the outer cylinder body 12.

The first guide part 633 of the present embodiment has a tapered shape.That is, the first guide part 633 is opened such that its widthgradually narrows toward the first opening 631. The first guide part 633(an example of the guide part) guides the first opening 631 to theholding part 12P to align the first opening 631 with the holding part12P.

The deformation permission part 634 includes an L-shaped groove 634T anda round opening 634H at an end of the groove 634T. The deformationpermission part 634 (an example of the deformation permission part)permits deformation of the baffle member 60 when the baffle member 60 isattached to the outer cylinder body 12 and the first neck part 632widens in the circumferential direction.

Second Held Part 64

As shown in FIG. 3A, the second held part 64 includes a second opening641, a second neck part 642 at the one side of the second opening 641,and a second guide part 643 at the one side of the second neck part 642.

The second opening 641 is a substantially round opening. The secondopening 641 has a circumferential width W1 that is slightly larger thanthe outer diameter D (see FIG. 2) of the holding part 12P. In the statewhere the baffle member 60 is attached to the outer cylinder body 12,the second opening 641 restricts the baffle member 60 from moving to theone side relative to the outer cylinder body 12.

Also, in the state where the baffle member 60 is attached to the outercylinder body 12, the second opening 641 restricts the baffle member 60from moving in the circumferential direction.

The second neck part 642 has a circumferential width W2 that is smallerthan the width of the holding part 12P. In the state where the bafflemember 60 is attached to the outer cylinder body 12, the second neckpart 642 restricts the baffle member 60 from moving to the other side.

The second guide part 643 of the first embodiment has a substantiallytriangle shape. That is, the second guide part 643 is opened such thatits width gradually narrows toward the second opening 641. The secondguide part 643 guides the second opening 641 to the holding part 12P toalign the second opening 641 with the holding part 12P.

Third Held Part 65

As shown in FIG. 3B, the third held part 65 includes a third opening651, a third neck part 652, and a third guide part (not shown in thefigure).

The basic structure of the third held part 65 is the same as that of thesecond held part 64.

As shown in FIG. 3B, the baffle member 60 of the first embodimentincludes the slit 61S between the second held part 64 and the third heldpart 65 in the circumferential direction. Thus, the slit 61S (an exampleof the deformation permission part) permits deformation of the bafflemember 60 when the second held part 64 is held by the holding part 12P,or when the third held part 65 is held by the holding part 12P.

In attaching the baffle member 60, the baffle member 60 is inserted inbetween the outer cylinder body 12 and the damper case 13 from the otherside of the cylinder unit 10. During this work, the structure of thedevice makes it difficult for an operator to confirm the position of theholding part 12P, which is located on the one side. However, the bafflemember 60 of the first embodiment includes multiple held parts (thefirst held part 63, the second held part 64, and the third held part65). This allows for easy assembly because the operator can insert thebaffle member 60 such that any one of the held parts is held by theholding part 12P.

With the above configuration, the baffle member 60 can be positioned bythe first held part 63, for example. Thus, the baffle member 60 of thefirst embodiment reliably prevents ruffle of the liquid surface, which,in turn, prevents mixing of bubbles in the liquid.

Operation of the Hydraulic Damper 1

FIGS. 4A and 4B are explanatory diagrams of how the hydraulic damper 1of the first embodiment works. FIG. 4A depicts oil flow during extensionof the hydraulic damper 1, and FIG. 4B depicts oil flow duringcompression of the hydraulic damper 1.

First, an explanation will be given of operation of the hydraulic damper1 during its extension.

As shown in FIG. 4A, during extension of the hydraulic damper 1, the rod20 moves to the other side relative to the cylinder 11. At this time,the piston valve 32 continues to close the piston oil ports 311.Further, the movement of the piston unit 30 to the other side reducesthe volume of the second oil chamber Y2. As a result, the oil in thesecond oil chamber Y2 flows out through the cylinder opening 11H intothe communication path L.

Then, the oil goes through the communication path L, the outer cylinderbody opening 12H, and the connecting channel 52R to flow into thedamping force changer 50. In the damping force changer 50, the oil flowwithin the connecting channel 52R is throttled by the solenoid valve 55.This throttling of the oil flow by the solenoid valve 55 generates adamping force. Thereafter, the oil flows out into the reservoir chamberR.

Also, pressure inside the first oil chamber Y1 becomes relatively lowerthan that inside the reservoir chamber R. For this reason, oil withinthe reservoir chamber R flows into a channel formed in the valve seat 41of the bottom valve unit 40. The oil then flows into the first oilchamber Y1.

Then, an explanation will be given of operation of the hydraulic damper1 during its compression.

As shown in FIG. 4B, during compression of the hydraulic damper 1, therod 20 moves to the one side relative to the cylinder 11. In the pistonunit 30, pressure difference between the first oil chamber Y1 and thesecond oil chamber Y2 causes the piston valve 32 to open the piston oilports 311. Thus, the oil within the first oil chamber Y1 flows outthrough the piston oil ports 311 into the second oil chamber Y2. Here,the rod 20 is present within the second oil chamber Y2. For this reason,the oil flowing from the first oil chamber Y1 into the second oilchamber Y2 is excessive in the amount equal to the volume of the rod 20within the second oil chamber Y2. Accordingly, the oil in the amountequal to the volume of the rod 20 within the second oil chamber Y2 flowsout through the cylinder opening 11H into the communication path L.

Then, the oil goes through the communication path L, the outer cylinderbody opening 12H, and the connecting channel 52R to flow into thedamping force changer 50. The oil flow within the damping force changer50 is the same as that during extension of the hydraulic damper 1 asdescribed above.

Also, as a result of the rod 20 moving to the one side relative to thecylinder 11, the oil within the first oil chamber Y1 flows into thechannel formed in the valve seat 41 of the bottom valve unit 40. Then,the oil opens the damping valve 42 of the bottom valve unit 40 to flowout into the reservoir chamber R.

To adjust the damping force by the damping force changer 50, thesolenoid valve 55 is controlled by the solenoid unit 51 (see FIG. 1).Specifically, distance between the solenoid valve 55 and the connectingchannel member 52 is changed by the solenoid unit 51. As the distancebetween the solenoid valve 55 and the connecting channel member 52narrows, the oil flow resistance increases, producing a larger dampingforce. On the other hand, as the distance between the solenoid valve 55and the connecting channel member 52 widens, the oil flow resistancedecreases, producing a smaller damping force.

Second Embodiment

FIG. 5 is an explanatory diagram of a baffle member 70 of the secondembodiment.

An explanation will be given of the hydraulic damper 1 of the secondembodiment. A difference of the hydraulic damper 1 of the secondembodiment from those of the other embodiments lies in the structure ofthe baffle member 70.

In the explanation of the second embodiment, similar components to thosein the first embodiment are denoted by the same reference numerals, anddetailed description thereof will be omitted.

As shown in FIG. 5, the baffle member 70 (an example of the disturbanceprevention member) includes a main body 71, an disturbance preventionpart 72 on the outer surface of the main body 71, and a held part 73formed at the one side.

Main Body 71

The main body 71 has an inner diameter substantially equal to the outerdiameter of the outer cylinder body 12. Also, the main body 71 has anouter diameter smaller than the inner diameter of the damper case 13(see FIG. 1). Further, in the second embodiment, the main body 71 of thebaffle member 70 is elongated to the one side (lower side) past thesolenoid connecting part 12J.

Further, the main body 71 includes a slit (not shown in the figure)extending in the axial direction. The slit has the same structure asthat of the slit 61S in the first embodiment. The slit divides the mainbody 71 in the circumferential direction of the main body 71.

Disturbance Prevention Part 72

The disturbance prevention part 72 includes multiple protrusions 721that protrude from the outer surface of the main body 71 to the outsidein the radial direction. The disturbance prevention part 72 preventsruffle of the oil surface within the reservoir chamber R.

The basic structure of the disturbance prevention part 72 is the same asthat of the disturbance prevention part 62 (protrusions 621) in thefirst embodiment.

Held Part 73

The held part 73 includes an opening 74, a neck part 75 at the one sideof the opening 74, a first guide part 76 at the one side of the neckpart 75, a straight part 77 at the one side of the first guide part 76,and a second guide part 78 at the one side of the straight part 77.

The opening 74 is a substantially round opening. The opening 74 has acircumferential width W1 that is slightly larger than the outer diameterD of the holding part 12P. In the state where the baffle member 70 isattached to the outer cylinder body 12, the opening 74 restricts thebaffle member 70 from moving to the one side.

Also, in the state where the baffle member 70 is attached to the outercylinder body 12, the opening 74 restricts the baffle member 70 frommoving in the circumferential direction.

The neck part 75 has a circumferential width W2 that is smaller than theouter diameter D of the holding part 12P. In the state where the bafflemember 70 is attached to the outer cylinder body 12, the neck part 75restricts the baffle member 70 from moving to the other side.

In the second embodiment, the opening 74 and the neck part 75 restrictthe baffle member 70 from moving to both the one side and the other sidein the axial direction.

The first guide part 76 has a tapered shape. That is, the first guidepart 76 is opened such that its width gradually narrows toward theopening 74. The first guide part 76 guides the opening 74 to the holdingpart 12P to fit the holding part 12P into the opening 74.

The straight part 77 is an axial groove having a predetermined width.The straight part 77 has a circumferential width W3 that is slightlylarger than an outer diameter D2 of the solenoid connecting part 12J.When the baffle member 70 is attached to the outer cylinder body 12, thestraight part 77 allows the baffle member 70 to be inserted to the oneside (lower side) past the solenoid connecting part 12J.

The second guide part 78 has a tapered shape. In other words, the secondguide part 78 is opened so that its width gradually narrows toward thestraight part 77. The second guide part 78 guides the straight part 77toward the solenoid connecting part 12J to fit the straight part 77 intothe solenoid connecting part 12J.

With the above configuration, the baffle member 70 can be positioned bythe held part 73, for example. Thus, the baffle member 70 of the secondembodiment reliably prevents ruffle of the liquid surface, which, inturn, prevents mixing of bubbles in the liquid.

Third Embodiment

FIG. 6 is an explanatory diagram of a baffle member 270 of the thirdembodiment.

An explanation will be given of the hydraulic damper 1 of the thirdembodiment. A difference of the hydraulic damper 1 of the thirdembodiment from those of the other embodiments lies in the structure ofthe baffle member 270.

In the explanation of the third embodiment, similar components to thosein the other embodiments are denoted by the same reference numerals, anddetailed description thereof will be omitted.

As shown in FIG. 6, the baffle member 270 (an example of the disturbanceprevention member) includes a main body 271, a disturbance preventionpart 272 on the outer surface of the main body 271, and a held part 273formed at the one side.

Basic structures of the main body 271 and the disturbance preventionpart 272 are the same as those of the main body 71 and the disturbanceprevention part 72 of the second embodiment, respectively.

Held Part 273

The held part 273 includes an opening 274, a second opening 275 at theone side of the opening 274, a straight part 276 at the one side of thesecond opening 275, and a guide part 277 at the one side of the straightpart 276.

The opening 274 is a substantially round opening. The opening 274 has acircumferential width W4 that is slightly larger than the outer diameterD of the holding part 12P. In the state where the baffle member 270 isattached to the outer cylinder body 12, the opening 274 restricts thebaffle member 270 from moving to both the one side and the other side inthe axial direction.

In the third embodiment, the opening 274 further restricts thecircumferential movement of the baffle member 270 within a certainrange.

The second opening 275 is a substantially round opening. The secondopening 275 has a circumferential width W5 that is slightly larger thanthe outer diameter D2 of the solenoid connecting part 12J.

The straight part 276 is a groove extending in the axial direction. Thestraight part 276 has a circumferential width W6 that is substantiallyequal to the width of the solenoid connecting part 12J. When the bafflemember 270 is attached to the outer cylinder body 12, the straight part276 allows the baffle member 270 to be inserted to the one side (lowerside) past the solenoid connecting part 12J.

The guide part 277 has a tapered shape. In other words, the guide part277 is opened so that its width gradually narrows toward the straightpart 276. The guide part 277 guides the straight part 276 toward thesolenoid connecting part 12J to fit the second opening 275 into thesolenoid connecting part 12J.

With the above configuration, the baffle member 270 can be positioned bythe held part 273, for example. Thus, the baffle member 270 of the thirdembodiment reliably prevents ruffle of the liquid surface, which, inturn, prevents mixing of bubbles in the liquid.

Fourth Embodiment

FIGS. 7A and 7B are explanatory diagrams of a baffle member 80 of thefourth embodiment.

An explanation will be given of the hydraulic damper 1 of the fourthembodiment. A difference of the hydraulic damper 1 of the fourthembodiment from those of the other embodiments lies in the structure ofthe baffle member 80.

In the explanation of the fourth embodiment, similar components to thosein the other embodiments are denoted by the same reference numerals, anddetailed description thereof will be omitted.

As shown in FIG. 7A, the baffle member 80 (an example of the disturbanceprevention member) includes a main body 81, a disturbance preventionpart 82 on the outer surface of the main body 81, and a held part 83 (anexample of the restricting part) formed at the other side.

The baffle member 80 of the fourth embodiment is attached to the otherside end of the outer cylinder body 12 in a suspended manner.

Main Body 81

As shown in FIG. 7B, the main body 81 has an inner diameter that issubstantially equal to the outer diameter of the outer cylinder body 12.Also, the main body 81 has an outer diameter that is smaller than theinner diameter of the damper case 13.

Further, the main body 81 includes a slit (not shown in the figure)extending in the axial direction. The basic structure of the slit is thesame as that of the slit 61S of the first embodiment. The slit dividesthe main body 81 in the circumferential direction of the main body 81.

Disturbance Prevention Part 82

As shown in FIG. 7A, the disturbance prevention part 82 includesmultiple protrusions 821 that protrude from the outer surface of themain body 81 to the outside in the radial direction. The disturbanceprevention part 82 prevents ruffle of the oil surface within thereservoir chamber R.

The basic structure of the disturbance prevention part 82 is the same asthat of the disturbance prevention part 62 (protrusions 621) of thefirst embodiment.

Held Part 83

As shown in FIG. 7B, the held part 83 includes an internal protrusion831 at the other side end thereof and a retraction part 832 at the oneside of the internal protrusion 831.

The internal protrusion 831 protrudes to the inside in the radialdirection. The internal protrusion 831 is positioned in between the rodguide 14 and the outer cylinder body 12 in the axial direction. In thepresent embodiment, the internal protrusion 831 is interposed betweenthe one side end of the rod guide 14 (an example of the opposed member)and the other side end of the outer cylinder body 12.

In the fourth embodiment, the internal protrusion 831 restricts thebaffle member 80 from moving to both the one side and the other side inthe axial direction.

At the one side of the internal protrusion 831, the retraction part 832defines a part whose diameter widens to the outside in the radialdirection. The retraction part 832 allows the internal protrusion 831 toextend linearly to the inside in the radial direction. Without theretraction part 832, the internal protrusion 831 may be obliquelyinclined for manufacturing reasons. To prevent this, in the fourthembodiment, the retraction part 832 is provided to ensure that theretraction part 832 extends in a direction perpendicular to the axialdirection.

With the above configuration, the baffle member 80 can be positioned bythe held part 83, for example. Thus, the baffle member 80 of the fourthembodiment reliably prevents ruffle of the liquid surface, which, inturn, prevents mixing of bubbles in the liquid.

Fifth Embodiment

FIGS. 8A and 8B are explanatory diagrams of the hydraulic damper 1 ofthe fifth embodiment.

An explanation will be given of the hydraulic damper 1 of the fifthembodiment. A difference of the hydraulic damper 1 of the fifthembodiment from those of the other embodiments lies in the structure ofthe baffle member 90.

In the explanation of the fifth embodiment, similar components to thosein the other embodiments are denoted by the same reference numerals, anddetailed description thereof will be omitted.

As shown in FIG. 8A, the baffle member 90 (an example of the disturbanceprevention member) includes a main body 91, projections 92 on the mainbody 91, and recesses 93 on the main body 91.

Main Body 91

When taken along the direction perpendicular to the axial direction, themain body 91 has a star-shaped cross section. The main body 91 includescrests 911 protruding to the outside in the radial direction, andtroughs 912 protruding to the inside in the radial direction so as tosink from the outside in the radial direction. Each crest 911 has aridge line 911P extending in the axial direction. Each trough 912 has atrough line 912V extending in the axial direction. The multiple crests911 and troughs 912 are alternately arranged in the circumferentialdirection of the main body 91.

In the fifth embodiment, each crest 911 (an example of the insidechannel) of the baffle member 90 forms an oil passage at the cylinder 11side. Also, each trough 912 (an example of the outside channel) of thebaffle member 90 forms an oil passage at the opposite side from thecylinder 11.

Further, as shown in FIG. 8B, the ridge line 911P of each crest 911contacts the inner surface of the damper case 13. The trough line 912Vof each trough 912 contacts the outer surface of the outer cylinder body12. Accordingly, the baffle member 90 is attached to the outer cylinderbody 12 such that the main body 91 is held between the outer cylinderbody 12 and the damper case 13. Thus, the main body 91 of the bafflemember 90 is restricted from moving to both the one side and the otherside in the axial direction.

The projections 92 protrude from the troughs 912 to the other side inthe radial direction. The height of each projection 92 is substantiallyflush with the ridge line 911P of each crest 911. When viewed from theinside in the radial direction of the baffle member 90, the projections92 are shaped so as sink to the outside in the radial direction.

The recesses 93 sink from the crests 911 to the inside in the radialdirection. The bottom of each recess 93 is substantially flush with thetrough line 912V of each trough 912. When viewed from the inside in theradial direction of the baffle member 90, the recesses 93 are shaped soas to protrude to the inside in the radial direction.

An explanation will be given of oil flow in the baffle member 90 of thefifth embodiment.

The solid arrow in FIG. 8A represents oil flow at the outside in theradial direction of the baffle member 90. Specifically, axial flow ofoil at the outside in the radial direction of the trough 912 isrestricted by the projection 92. This causes the oil to flow in thecircumferential direction along the recess 93 into the adjacent trough912. In this way, the oil is restricted from flowing smoothly in theaxial direction at the outside in the radial direction of the bafflemember 90, and this prevents ruffle of the liquid surface.

The dashed arrow in FIG. 8A represents oil flow at the inside in theradial direction of the baffle member 90. Specifically, axial flow ofoil at the inside in the radial direction of the crest 911 is restrictedby the recess 93. This causes the oil to flow in the circumferentialdirection along the projection 92 into the adjacent crest 911. In thisway, the oil is also restricted from moving smoothly in the axialdirection at the inside in the radial direction of the baffle member 90,and this prevents ruffle of the liquid surface.

With the above configuration, the baffle member 90 can be positioned by,for example, the main body 91 itself being held between the outercylinder body 12 and the damper case 13 in the radial direction. Thus,the baffle member 90 of the fifth embodiment reliably prevents ruffle ofthe liquid surface, which, in turn, prevents mixing of bubbles in theliquid.

In order to more tightly restrict movement of the baffle member 90 inthe axial direction, the baffle member 90 of the fifth embodiment mayfurther include, for example, the first opening 631 and the first neckpart 632 of the first embodiment. Also, in order to more tightlyrestrict movement of the baffle member 90 in the axial direction, thebaffle member 90 of the fifth embodiment may further include, forexample, the internal protrusion 831 of the fourth embodiment protrudingto the inside in the radial direction.

In the above embodiments, the oil chambers (the first oil chamber Y1 andthe second oil chamber Y2), the reservoir chamber R, and thecommunication path L are formed by a so-called triple tube structure,which consists of the cylinder 11, the outer cylinder body 12, and thedamper case 13, each being cylindrical. However, these chambers and pathare not necessarily formed by the triple tube structure. For example,the baffle member of any of the first to the fifth embodiments may beused in a so-called double tube structure consisting of the cylinder 11and the damper case 13.

REFERENCE SIGNS LIST

1 Hydraulic damper

11 Cylinder (an example of the first cylinder)

12 Outer cylinder body 12 (an example of the second cylinder)

13 Damper case (an example of the third cylinder)

30 Piston unit (an example of the partitioning unit)

40 Bottom valve unit

50 Damping force changer

60 (70, 80, 90, 270) Baffle member (an example of the disturbanceprevention part)

L Communication path

R Reservoir chamber (an example of the liquid chamber)

The invention claimed is:
 1. A hydraulic damping device comprising: acylinder unit storing liquid; a liquid reservoir outside the cylinderunit, the liquid reservoir retaining liquid; a partitioning unitconfigured to move in an axial direction inside the cylinder unit, thepartitioning unit partitioning a space inside the cylinder unit into afirst oil chamber and a second oil chamber each storing liquid; adisturbance prevention member separate from the cylinder unit andconfigured to be attached to the cylinder unit, the disturbanceprevention member including a main body located in the liquid reservoirand a protrusion protruding from the main body, the disturbanceprevention member being configured to prevent disturbance of a liquidsurface of liquid within the liquid reservoir; a damping force generatorat an outside of the cylinder unit in a radial direction, the dampingforce generator being configured to permit flow of liquid between thedamping force generator and the cylinder unit via a connecting part, thedamping force generator being configured to generate a damping force byimparting resistance to flow of the liquid that results from thepartitioning unit moving in the axial direction; a cylinder protrusionat a different position on the cylinder unit different from theconnecting part, the cylinder protrusion protruding from the cylinderunit in the radial direction; a restricting part provided to thedisturbance prevention member, the restricting part including a heldpart held by the cylinder protrusion, the restricting part beingconfigured to restrict the disturbance prevention member from moving toboth one side and the other side in the axial direction; and adeformation permission part configured to permit deformation of the heldpart when the disturbance prevention member is attached to the cylinderunit.
 2. The hydraulic damping device according to claim 1, wherein theheld part includes an open end at the one side in the axial directionand a closed end at the other side in the axial direction, and includesan opening surrounding the cylinder protrusion.
 3. The hydraulic dampingdevice according to claim 2, wherein the held part includes a guidepart, the guide part having an opening width decreasing toward theopening, the guide part being configured to guide the held part towardthe cylinder protrusion when the disturbance prevention member isattached to the cylinder unit.
 4. The hydraulic damping device accordingto claim 2, wherein the opening includes: a first part having an openingwidth larger than a width of the cylinder protrusion; and a second partat the one side relative to the first part, the second part having anopening width smaller than the opening width of the first part.